The ? (alpha) scale is a non-octave-repeating musical scale. In one version it splits the perfect fifth (3:2) into nine equal parts of approximately 78.0 cents.[] In another it splits the minor third into two equal parts,[1] or four equal parts of approximately 78 cents each[2]Play(help·info). At 78 cents per step, this totals approximately 15.385 steps per octave. The scale step may be precisely derived from using 9:5Play(help·info) to approximate the interval ​,[3] which equals 6:5 Play(help·info).